[gimp] Bug 770600 - Fix broken export to PBM

[Michael Natterer <mitch src gnome org>]

commit 3ab1389b9b4821d28c64ebf562ca0abd7ffb7138
Author: Mihail Zenkov <mihail zenkov gmail com>
Date:   Sun Sep 4 17:19:08 2016 +0200

    Bug 770600 - Fix broken export to PBM
    
    Use the drawable's (indexed bitmap) format instead of "Y' u8" when
    exporting to PBM, this got broken when porting to GEGL.

 plug-ins/common/file-pnm.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/plug-ins/common/file-pnm.c b/plug-ins/common/file-pnm.c
index 1bc4615..12bd34a 100644
--- a/plug-ins/common/file-pnm.c
+++ b/plug-ins/common/file-pnm.c
@@ -1228,7 +1228,7 @@ save_image (GFile     *file,
       if (pbm)
         {
           header_string = "P1\n";
-          format = babl_format ("Y' u8");
+          format = gegl_buffer_get_format (buffer);
           np = 0;
           rowbufsize = xres + (int) (xres / 70) + 1;
           saverow = pnmsaverow_ascii_pbm;
@@ -1272,7 +1272,7 @@ save_image (GFile     *file,
       if (pbm)
         {
           header_string = "P4\n";
-          format = babl_format ("Y' u8");
+          format = gegl_buffer_get_format (buffer);
           np = 0;
           rowbufsize = (gint) ceil ((gdouble) xres / 8.0);
           saverow = pnmsaverow_raw_pbm;